<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }
        /* .bigbox {
            box-sizing: border-box;
        } */
        li {
            list-style: none;
        }
        body {
            height: 1000px;
        }
        /* 用双伪元素清除浮动 */
        .clearfix:before,
        .clearfix:after {
            content: "";
            display: table;
        }
        .clearfix:after {
            clear: both;
        }
        .clearfix {
            *zoom: 1;
        }
        .bigbox {
            width: 1200px;
            height: 400px;
            margin: 200px auto;
            background-color: pink;
        }
        .bigbox ul {
            padding-top: 20px;
        }
        .bigbox ul li {
            float: left;
            width: 200px;
            height: 150px;
            background-color: skyblue;
            margin: 0 20px;
        }
        .box {
            width: 1200px;
            height: 100px;
            background-color: purple;
        }
        .siz {
            width: 200px;
            height: 200px;
            background-color: pink;
            margin: 0 auto;
            border: 10px solid red;
            padding: 20px;
            /* 这个是让siz这个盒子不会被撑开 */
            box-sizing: border-box;
        }
        .son {
            width: 140px;
            height: 140px;
            background-color: purple;
        }
    </style>
</head>
<body>
    <div class="bigbox">
        <ul class="clearfix">
            <li>1</li>
            <li>2</li>
            <li>3</li>
            <li>4</li>
            <li>5</li>
        </ul>
        <div class="box">
            我在哪，我是谁
        </div>
    </div>
    <div class="siz">
        <div class="son"></div>
    </div>
</body>
</html>